1. Blackening and phosphating
Blackening:
A process in which steel or steel parts are heated to an appropriate temperature in air-water vapor or chemical drugs to form a blue or black oxide film on the surface. Also become bluing.
Phosphating:
The process of immersing the workpiece (steel or aluminum, zinc) into a phosphating solution (some acid-based phosphate-based solution), and depositing a layer of water-insoluble crystalline phosphate conversion film on the surface is called phosphating.
2. Anodizing
Mainly refers to the anodic oxidation of aluminum and aluminum alloys. Anodizing is the process of immersing aluminum or aluminum alloy parts in acidic electrolyte and acting as an anode under the action of an external current to form an anti-corrosion oxide film layer on the surface of the parts that is firmly combined with the substrate.
This oxide film has special characteristics such as protection, decoration, insulation, and abrasion resistance.
Before anodizing, it must undergo pretreatments such as polishing, degreasing, and cleaning, and then washing, coloring, and sealing.
Application:
It is often used in the protective treatment of some special parts of automobiles and airplanes, as well as the decorative treatment of handicrafts and daily hardware products.